Air-cooled outboard motor



July 5, 1960 cya. BENsoN .ET/u. v

' AIR-000mm oUTBoARD MOTOR 2 Sheets-Sheet 1 Fi] ed May 2, 1958 C. B.BENSON ET AL AIR-COOLED OUTBOARD MOTOR July 5, 1960 Filed May 2, 1958 2Sheets-Sheet 2 INVENTORS CLARENCE G-CARLSON CARL B- BENSON @MTMAttorneys United States Patent AIR-COOLED OUTBOARD MOTOR Carl B. Benson,626 W. 116th, and Clarence G. Carlson, 234 W. 49th, Seattle, Wash.

Filed May 2, 1958, Ser. No. 732,469

13 Claims. (Cl. 11S-17) This invention relates to outboard motors,particularly one in which the power plant is an air-cooled internalcombustion engine and having an underwater discharge for the exhaustgases.

It is standard practice with modern outboard motors, in carrying exhaustgases from the engine to an underwater discharge opening, to pass thesame along the interior of the motors power leg. With water-cooledengines, pumped water issuing from the jackets of the engine is commonlymixed with said exhaust gases, as the same pass along the interior ofthe power leg, in an effort to preclude the above-water portion of theleg from becoming unduly hot. Air-cooled engines Ahave in some instancesfinned their legs, and in other instances have employed a pump for thesole purpose of lifting water to the head end of the leg and therecharging the same into the exhaust gases. Finning has beenonlymoderately effective, wherefore most outboard motors heretoforeproduced, whether air-cooled or water-cooled, have commonly incorporateda water pump. Aside from the liability of the opening to the pumpbecoming clogged from sea-weed or other water-borne foreign matter, orthe pump itself giving out, the inside surfaces of the power leg aresubject to corrosion when water being pumped is sea water. Where thesurfaces attacked arerelatively inaccessible for periodic cleaning thedamage from cor rosion can be substantial. l

The present invention, for its general object, aims to provide anoutboard motor in which an air-,cooled engine is used for the powerplant and with the exhaust gases being passed through the interior ofthe power leg to obtain an underwater exhaust, and so engineered thatsuch power leg can be maintained in a cool condition, relativelyspeaking, without recourse to water as a cooling medium.

It is a more particular object to provide an outboard motor of thecharacter described having a blowercontained in a housing placed tooccupy an intervening position between the engine and the power leg, andemploying a rapidly moving column of air blown by said blower as a meansof dissipating heat from such housing and the upper portion of the powerleg.

As a further particular object the invention aims to provide an outboardmotor of the character described peculiarized in that the exhaust gasesleaving the engine are caused to by-pass the blower compartment, incourse thereof traversing a radiator exposed to the atmosphere so that asubstantial portion of the contained heat of combustion is dissipatedfrom said gases before the same have access to the interior of the powerleg.

A yet further important object is to so engineer a motor of thedescribed character as to preclude exhaust gases from within the powerleg entering the blower compartment, thus preventing exhaust fumes frombeing charged into the atmosphere together with the column of airexpelled from said compartment.

Further still more particular objects and advantages will, with theforegoing, appear and be understood in 2,943,592 Patented July 5, 1960the course of the following description and claims, the inventionconsisting in the novel construction and in the adaptation andcombination of parts hereinafter described and claimed.

In the accompanying drawings:

Figure l is a view partly in side elevation and partly in verticalsection to illustrate an outboard motor constructed to embody thepreferred teachings of the present invention.

Fig. 2 is a fragmentary transverse vertical sectional view drawn to anenlarged scale on line 2 2 of Fig. l.

Fig. 3 is a fragmentary transverse vertical sectional view on line 3-3of Fig. 4; and

Fig. 4 is a horizontal sectional view on line 4--4 of Fig. l, the scaleemployed in Figs. 3 and 4 corresponding to that of Fig. 2.

The drawings exemplify the invention as applied to one of severalinternal combustion engines Well known in the industry which areconsidered as more or less of an all-purpose design in that the same are`adapted to use as the power head for sundry machines including that ofan outboard motor. Salient to such engine design is the provision of amounting base 10 through which a vertical extension 11 of the crankshaft projects, and having about the perimeter a plurality ofcircumferentially spaced bosses 12 vertically drilled for reception ofmounting bolts 13. Distinguished from engines which have been expresslyengineered for use in outboard motors, the allpurpose power head hereillustrated presents a side exhaust opening 14 ,exposed to view abovethe mounting base and which is tapped to receive a nipple on which v acan muffler is commonly mounted. By reason of the comparatively lowefficiency of this type of muffler with its attendant high noise level,and the added objection to above-water delivery of exhaust gasesconsidered from the aspect of noxious fumes, such an exhaust is notpractical in an outboard motor.

The power leg 15 employed in the present invention is or may beconventional, being a hollow structure with the interior closedexcepting for an underwater exhaust opening. Said hollow interiorcarries exhaust gases to the underwater exhaust opening and will behereinafter termed the tail passage. Introduced between this leg and themounting base 10 is a blower housing 20. The housing has somewhat of abell shape, invertedly mounted `so that the open mouth lies at the top,and has handles, as 21 and 22, projecting fore and aft. A steering arm23 is pivoted, as at 24, to the forwardly extending handle. Bolts 25secure the housing Vto the power leg, and the bolts 13 secure the sameto the power head, the latter threading into upstanding bosses 26 whichregister with the bosses 1-2 and separate the housing from the leg so asto define a moderately wide interstice 28 therebetween. This intersticefunctions as the induction opening for an air blower 27 received withinthe housing. Eduction openings are denoted by 30 and occur at spacedintervals of the circumference in a flared portion of the housing wallexposed above the power leg. The -blower is carried by a hub 31 which iskeyed to the shaft extension 11 of the power head, and in the bottom ofthe hub is a spline socket receiving the splined upper end 32 of lthepower legs vertical drive shaft 34. A bearing for such upper end of thedrive shaft is provided by a bushing 35 which is carried by the baseWall of the blower housing, this base wall being otherwise imperforatein order that the interior of the blower housing will be completelyisolated against access of fumes from the interior of the leg.

Said base wall, aft of the bearing, presents a ceiling pocket 36 exposedto the interior` of the power leg. The side wall of the blower housinghas a bored and counterbored horizontal opening 37 leading to thispocket-in a position parallel with and spaced below the engines exhaustopening 14, and received through this opening is one branch 38 of a-generally L-shaped tail pipe. The other branch 40 isarranged to dependinto the power leg and is preformed with bends (see Fig. l.) necessaryto follow theI interior profile contour of the power leg while beingspaced therefrom. As here shown the tail pipe has its two branchessilver-soldered to. a connecting elbow 42 but ,self-evidently' could" bepreformed from a single length of pipe.

The outer end of the branch 3 8 connects by a iiare fitting 43 with thelower end of a finned pot-radiator 44. An asbestos washer 45 receivedwithin the counterbore of the wall opening 37 acts with a libre sleeve46 to heat-insulate the branch 38. A11v exhaustnipplef47- having rightand left hand threads upon-r its. two ends connects the upperendof'the.pot-radiator with the exhaust opening 14. Y

It is thought that the invention will havev been clearly understood fromthe foregoing detailed description of the now preferred illustratedembodiment. The potradiatorsubstantially reduces the temperature of theexhaust gases before the same enter the interior of the power leg andthis, acting in conjunction with direct radiation from the head end ofthe power leg to the air column which is` blown downwardlyy around thesame, and transfer ofsaid heat. yby conduction to: the air-cooled Walls.of the blower housing-effectively maintains. the upper portion of thepower leg at a moderate temperature. It will be seen that the interiorchamber of the pot radiator depends somewhat below the outlet open,-ing. Also, the tail pipe is moderately smallerV than the engines exhaustport, and considerably smaller than' the pot-radiator. The resulty is toproduce withinthey chamber of the pot-radiator a surge which operateslike. a bale to momentarily suppress the gasesv and providey anaddedtime interval in which to transfer heatv through. the walls of theradiator for dissipation from the` radiation fins.

The carrying handles 21 andr22 are aconstituted part of the blowerhousing andare hence little more than warm to the touch even though themotor is liftedv immediately after stopping the engine.

No limitations are to be implied andi it is our intention that thehereto annexed claims be given the broadest interpretation to which thelanguage fairly admits.v

What we claim is:

l. InA an outboard motor, a power headY providing an air-cooled internalcombustion engine with a vertical extension of the engines crank shaftexposed below said head, a hollow power leg carrying a propeller at thebottom end and having a drive shaft for said wheel extending upwardlythrough the interior with its upper end exposed, the hollow interior ofsaid leg leading-to an underwater exhaust opening, a' blower housingrigid with the power leg and the power head in an intervening positionybetween the same, a rotary blower in said housing, and means forpassing the drive from said crank extension to the blower and to theupper end of the drive shaft, said blower being arranged and adapted toblow cooling air downwardly over saidv power leg, means being providedfor delivering exhaustv gases from the enginev to the interior of thepower leg.

2. In an outboard motor, a power head providing an air-cooled internalcombustion engine with a vertical extension of the engines crank shaftexposed below said head and having an exhaust opening at the side, aVhollow power leg carrying a propeller atthe botto-1n end and having adrive shaft for saidV propeller extending upwardly through the interiorwith its upper' end exposed, the hollow interior of said leg leading toan underwater exhaust opening, a blower housingv made rigid with saidpower leg and the power head in an intervening position between thesame, a rotary blower in. said-housing, means for passing the drive fromsaid; extension. to the blower and to the upper end of the drive shaft,said blower being arranged and adapted to blow cooling air downwardlyover said power leg, and means lying outside the blower housing `forcarrying the exhaust gases from said exhaust opening of the engine intothe hollow interior of the power leg.

3. Structure according to claim 2 in which the means last recitedincludes a muffler.

4. Structure according'to claim- 2 inl which the means last recitedincludes a radiator presenting exterior iins exposed to the atmosphere.

5. Structure according to claim 2 in which the means last recitedincludes a "pot-radiator presenting external ns and being formed:interiorly with Vachamber which connects at a point adjacent one endwith an admission pipe which leads from the engine and connects at apoint adjacent the other end with an emission pipe leading to saidhollow interior of the power leg, the gases havingV a runof substantiallength between said admission and emission pipes, the cross-section ofsaid interior chamber being large by comparison with. that of both the.admission pipe and the emission. pipe.

6.. Inan outboard motor, al propeller, a power leg supporting saidpropeller at its lower end and presenting a closed tailpassage leadingfrom the legs upper end to an underwater exhaust opening, a power headsurmounting said leg, andproviding an air-cooled internal combustionengine drive-coupled to the propeller, means piping exhaust gases fromtheengine to the upper end of said tail passage, and means drivenfromthe engine and occupying a position between said engine and the legfor blowing a cooling4 column. of air over the exterior surface of thepower legs upper end.

7. In an outboard rno'tor, a propeller, a power leg supporting Asaidpropeller at its lower end. and presenting a closed tail passage leadingfrom the legs upper end to an underwater'exhaust opening, a power headsurmounting said leg and providing an air-cooled internal combnstionengine drive-coupled to the propeller, and means piping exhaust gasesfrom the exhaust port of the engine to the upper end of said tailpassage and including within the length thereof a radiator presenting.exterior tins exposed to the atmosphere, the gas-conducting connectionfrom the radiator to the tail passage comprising a pipe heat-insulatedfrom the power leg.

8'.Y In an outboard mo'tor, a propeller, a. power leg supporting saidpropeller at its, lower end and presenting a closed tail. passageleading from the leg/s upper endv to underwater exhaust opening, a powerhead surmounting said leg and providing an air-cooled internalcombustion engine drive-coupled to the propeller, a radiator lo'catedalongside the power head presenting a pot. charn- -ber ofsubstantiallength and having exterior fins exposed to the atmosphere, andgas-conducting connections leading from the exhaust port of the engineto the pot chamber and Vfrom the pot chamber to the upper end of thetail passage, the inlet opening. to the pot chamber being locatedadjacent one end of said chamber and the outet opening being located ina position distal to the inlet opening. and spaced. from thek other endof said chamber.

9. Structure according'to claim 8, the connection from the` engine tothe pot chamber comprising an exhaust pipe formed with right and lefthand threads upon opposite ends, the. connection from the pot chamber tothe tail passage comprising ay tail pipe isolated from the walls of thepower leg and attachedv to the radiator by a flare fitting.

.1.0. In. an. out-boardA motor, a propeller, a power leg supporting saidpropeller at its. lower end, providing a Yhollow interior open aty thetop and leading to an underwater exhaust, and having a drive shaft forthe propeller extending upwardly through said hollow interior with itsupper end exposed a blower'housing securedI in surmounting: relation tothe' power legand so formed as to provide: flared side walls whichproject upward and outy 'zw -2 wardly beyond the leg, the base portionof said blower housing providing a journal bearing for the upper end ofthe drive shaft and serving as a closure for the top opening of thepower leg, said flared side walls having a plurality of openings thereinspaced at intervals of the circumference, a blower having its hub iiXedto the upper end o'f the drive shaft for rotation in the blower housing,a power head secured in surmounting relation to the blower housing andproviding an air-cooled internal combustion engine drive-coupled to thehub of the blower, an opening at the top of the blower housing forintroduction of air to the blower, the blower acting by its rotation toforce said air downwardly and discharge the same through said wallopenings about the head end of the power leg, and a connection forconducting exhaust gases located outside the blower housing and leadingfrom the exhaust port of the engine into the hollow interior of thepower leg.

11. Structure according to claim 10 having a carrying References Citedin the le of this patent Y UNITED STATES PATENTS Junkers Dec. 2, 19241,824,740 Johnson et al Sept. 22, 1931 2,256,831 Karey Sept. 23, 19412,326,224 Jackson Aug. 10, 1943 2,528,480 Wilson et al. Oct. 31, 19502,737,774 Stiers Mar. 13, 1956

